1. Field of the Invention
The present invention relates to a tire status monitoring system for monitoring tire conditions, such as tire air pressure and temperature, to improve the safety of vehicular operation, and more particularly to a tire status monitoring system capable of varying the transmission periods for transmitting tire condition data according to an operation mode to reduce consumption power of vehicle batteries.
2. Description of the Related Art
As traffic has increased, in order to improve the safety of automotive operation, a tire status monitoring system may be provided so that a driver inside the vehicle can recognize vehicular tire conditions, mainly tire air pressure. Methods of monitoring the tire air-pressure by such a tire status monitoring system are classified into the indirect detecting method where a rotation number of the vehicular wheel changes indicates a difference in tire air pressure (which is described in U.S. Pat. No. 5,900,543) and the direct detecting method of directly detecting the tire air pressure by installing a pressure sensor inside the tire (which is described in U.S. Pat. No. 6,705,152).
The indirect detecting method of using the change of rotation number of the vehicular wheel is economical in cost and requires less installation work. But, such method has problems in that the measuring error may be excessive so that it is easy for a warning signal error to occur, only a relative comparison of pressures to other readings is possible and any correction work of the equipment is complicated.
The system of directly measuring the tire air pressure by installing pressure sensors inside the tire comprises a transmitter which is installed in a tire to wirelessly transmit the tire condition and a receiver which is installed on a dashboard to inform a driver of the tire condition. Here, each transmitter is installed at the wheel in order to measure the air pressure within the tire, and because each transmitter is driven by a battery, the operation of the transmitter is stopped in the case where the battery is fully consumed or dead. In this case where the battery has been consumed, the tire must be separated from the wheel in order to exchange this battery. Therefore, there is a problem in that it is very difficult to exchange the battery. In addition, the transmitter is assembled with high precision to endure the rough conditions within the tire. Accordingly, there is another problem in that the opening of transmitter case for exchange of the battery may result in lowering the reliability of the transmitter.